In the field of displaying technology, the liquid crystal display is widely used due to advantages such as small volume, low power consumption, free of radiation and high resolution. FIG. 1 is a schematic sectional view of a periphery region of a liquid crystal display. As shown in FIG. 1, a common liquid crystal display includes a color film substrate 10 and an array substrate 20 which are arranged opposite to each other, and a liquid crystal layer (not shown in the figure) provided between the two substrates. A periphery of the color film substrate 10 and a periphery of the array substrate 20 are adhered via a sealant 30. A black matrix 11 and an alignment film 12 are provided at the side of the color film substrate 10, and the array substrate is provided with an alignment film 12. A display region of the liquid crystal display is completely covered by the alignment films 12. In addition, the area of coverage of the alignment films 12 is usually larger that the area of the display region, to ensure that the display region is completely covered by the alignment films.
Generally, one motherboard includes multiple unit display screens. For the producer of display panel, the more unit display screens obtained by cutting a same motherboard is, the higher the production-line profitability is. To distinguish respective unit display screens, each unit display screen is marked with a Panel ID (mark) during the manufacture. Since the Panel IDs for respective unit displays are different, currently, a main approach in the production-line is marking the respective unit displays successively by using a laser pen. If the number of unit display screens in one motherboard glass is small, the work of Panel ID marking is relative simple and little productivity of the production-line is taken. However, if the number of unit display screens in one motherboard glass is relative large, the work of Panel ID marking is relative complicated and much productivity of the production-line is taken. Particularly, sizes of unit display screens manufactured via respective generational lines of panels currently turn smaller and smaller, there are hundreds of unit display screens on a substrate of a motherboard glass, and the work of Panel ID marking turns relative hard. Sometimes the Panel IDs are not marked in consideration of the productivity of the production-line; in this way, issues occurring in latter manufacturing processes cannot be traced back to former processes, thereby greatly decreasing efficiency of the production-line. On another hand, periphery regions of display screens having small sizes currently turn smaller and smaller, and the Panel IDs may occupy some space; hence, it is urgent to provide an effective approach for marking Panel IDs on displays having small sizes.